Fuse plug construction



March 17, 1942. L, sg 2,276,703

FUSE PLUG CONSTRUCTION Filed April 2, 1941 :WIWIII INVENT OR.

Patented Mar. 17, 1942 UNITED STATES EATENT OFFICE 7 Claims.

This invention relates to improvements in fuse plug constructions andmore particularly to improvements in the manner in which fuse strips aresecured in the center terminals of fuse plugs.

An object of the present invention is to provide a fuse plugconstruction wherein the fuse strip is secured to one of the terminalsin an improved manner.

Another object of the invention is to provide a new type of connectionbetween the fuse strip and one of the terminals of a fuse plug.

A further objectv of the invention is to provide a connection between afuse: strip and one of the terminals of a fuse plug; which connection isof such character as to maintain good electrical contact between theparts. and to simplify the process of manufacture thereof.

A further object of the invention is to provide an. improved attachment,as before described, in which a fuse strip is held in a hollow terminalby means of a resilient spring member.

An additional object of the invention is to provide an arrangementwhereby a fuse strip is held in a hollow terminal member by means of asubstantially U-shaped spring retaining member.

A further object of the invention is to provide an arrangement as.before described, in which the terminal member has a hollow portion ofsubstantially rectangular or square shape in cross section and in whichthe substantially U-shaped spring retaining member is made from flatstock.

A still further object of the invention is to provide anarrangement asdescribed in which the terminal has a hollow portion of circular shapein cross section and in which the substantially U-shaped. member hascurved leg portions to conform to the general shape of the hollowportion.

Incarrying out the foregoing and other objects of the invention, a. fuseplug is constructed in such fashion as to be. made up of a body portionhollowed out and having-a through aperture in the bottom, thereof. Inaddition, use is made of a shell part cooperating with the body part andsecured thereto by an externally threaded metallic ferrule whichservesas one terminal as the plug; one end olithe fuse strip beingsecured thereto in conventional fashion. The second terminal member usedin this fuse plug construction is so shaped asto have a hollow partextending through the aperture in the body and having a flanged part, ordisc, underlying the bottom edge or surface of the body. This hollowportion may be of any desired shape in cross section, such as.rectangular, square, round, polyg- 68 onal, hexagonal, or any othersuitable shape. For convenience and brevity, two shapes are illustratedin the accompanying drawing, The terminal member, including the hollowportion, can be secured in the aperture in the body either by turning apart of the upper edge thereof over against the upper surface of thehollowed out part of the body or this terminal may be retained in theaperture by a frictional tight fit.

The hollow part is provided to receive one end of the fuse strip (theother end of which is secured to the outer ferrule) and the end withinthe central terminal is retained in place by a substantially U-shapedmetallic spring member inserted into the terminal in such fashion thatone leg of the spring bears against the strip within the terminal andthe other leg bears against the wall of the terminal. This spring membercan have serrated edges or surfaces if desired, to aid in retaining thesame in assembly with the strip end and with the terminal.

Other features, objects and advantages of the invention will be apparentby reference to the following detailed description of the accompanyingdrawing, wherein Fig. 1 is a horizontal section of a part of a fuse plugembodying the invention, such section being taken substantially on theline I| of Fig. 2;

Fig. 2 is a side View partially in vertical section of the same device,taken substantially on the line 22 of Fig. 1;

Fig. 3 is a side elevation of a spring retaining member utilized in theinvention;

Fig. 4 is a plan View of a body member plus a strip assembly of amodified form of the invention, and

Fig. 5 is a section taken substantially on the line 5--5 of Fig. 4.

Referring now to the drawing and particularly to Figs. 1 to 3 inclusive,l0 indicates a body for a fuse plug construction, such body being madeof some suitable insulating material. The body as shown, has a dependingportion II with a flat bottom 12, flange part l3 and an upstandingtubular part M. In conjunction with the base l0, use is made of a shell15 of glass, or other conventional material, and a metallic ferruleithaving a bottom flange IT. This metallic ferrule H3 is formed to providea thread and preferably the shell l5 has its outer surface threaded sothat the ferrule l6 can be screwed onto the shell IE to hold the partsin assembly with the flange ll underlying the flange l3. These parts areof conventional fashion and are shown in the drawing only to illustrateone type of generally known fuse plug construction. It is to beunderstood that other types of construction can be used in the presentinvention without departing from the spirit and scope thereof.

The body II) has a through central aperture 25 to receive a hollow part2| of a terminal member. This hollowed out part 2I has a flared bottomedge portion 22 to which is secured a disc member 24, the edges of whichare curled around the flared out part as shown in Fig. 2. In thearrangement illustrated in Figs. 1 and 2, the aperture 20 is ofsubstantially square shape in cross section and consequently the hollowpart 2| of the terminal is likewise of square shape in cross section.This hollow part is so dimensioned as to be insertable into the aperture26) with a very tight frictional fit therein. For this reason the bottompart of the aperture wall is rounded out to facilitate introduction ofthe terminal into the recess. be sufiicient to retain the terminal inassembly with the base, but if desired, opposite parts 25 of the upperedge portion of the hollow part H can be spread outwardly over the uppersurface of the material surrounding the aperture 28. This spreadingaction can be accomplished by a suitable tool.

A fuse strip 3!] of the usual type has one end thereof retained in thehollow part 2| of the central terminal in such fashion that goodelectric contact is maintained between the end of the strip and theterminal. For this purpose, use is made of a spring member 35 ofsubstantially U-shape. The spring member like the terminal can be madeof any suitable metal, such as copper, brass, spring bronze or any otherdesired suitable material. Likewise, the spring 35 may have serrations36 on the surfaces of the leg portions thereof, which serrations are sodisposed as to permit ready introduction of the spring into the terminalbut as to resist withdrawal of the same therefrom.

The fuse strip 30 of the retaining member 35 can be assembled with theterminal either before or after the terminal has been assembled with thebody I0. If desired, the terminal can be placed in a suitable supportand the fuse strip and retaining member insertable thereinto either byhand or by proper mechanism. After such insertion has been accomplished,the strip and terminal may be introduced into the aperture 29 and thenthe terminal forced home into the position shown in Fig. 2. If the partsare so dimensioned as to provide a tight frictional fit, furtherclinching of the terminal may not be necessary, but as a safeguardagainst adventitious removal of the terminal, parts 25 thereof can beflared as shown. The spring retaining member 35, however, increases thefriction between the hollow part of the terminal and the aperture 20,due to the tendency of the spring 35 to expand, and consequently thefriction between the wall of the aperture and the wall of the hollowpart of the terminal is accentuated. This arrangement therefore servesadmirably to retain a fuse strip in assembly with the central terminalof a fuse plug.

While the assembly shown in Figs. 1 to 3 make use of a terminal having ahollow part of substantially square outline, it is evident that suchhollow part may have any other suitable outline. The square outlineshown is the preferred form since the fit between the terminal and thebody is of such obvious character as to prevent rotation between theseparts. Any shape other than In some cases this frictional fit will roundlikewise will produce the same results.

However, it may be desirable to use a terminal having a hollow part ofcircular shape in cross section and such an arrangement is shown inFigs. 4 and 5. In these figures the parts are substantially similar tothose previously described and only the body member III] and terminaland fuse strip are shown. The body member III) has a depending part III,a flat bottom portion H2, a flange part H3, and a tubular part I I4.This body part likewise has a through aperture I but such aperture is ofcircular shape in cross section. In conjunction with this body, use canbe made of a central terminal member having a hollow part I2I likewiseof circular shape in cross section and flared outwardly as at I22. Adisc I24 is secured to the hollow part in the manner previouslydescribed. Similarly, opposite parts I25 can be flared outwardly toretain the terminal in assembly with the body. A fuse strip I isretained in the terminal by means of a substantially U-shaped spring member I35, which spring member however, has the leg portions thereofrounded slightly as shown at I40 so that these leg portions can conformto the shape of the hollow wall part I20 and cause the fuse strip tolikewise assume a roiuided shape with such wall.

As in the case of the Figs. 1 and 2, embodiment of the invention, theterminal and fuse strip can either be preassembled before introcluctioninto the body of the plug or, if desired, the terminal can first beassembled with the body and then the fuse strip and spring retainingmember introduced into the terminal after such attachment. The springmember I may have serrations on the outer surface of the leg partsthereof as in the case of the member 35 if desired, but it is to beunderstood that in any event, such serrations may be omitted if the sameseems to be warranted.

From the foregoing it will be seen that the present invention providesnew, simple and efficient arrangements for securing fuse strips to thecenter electrodes of fuse plugs, which arrangements materially reducethe cost of manufacture without sacrificing any advantages heretoforeobtained by the use of solder or other expensive attaching devices. Thespring retaining member assures that the fuse strip will be forced intosuch intimate contact with a part of the terminal as to assure goodelectrical contact between these parts. The invention can be modifiedbeyond the illustrated embodiments and accordingly, any limitationsimposed thereupon are to be only those set forth in the followingclaims.

What is claimed is:

1. In a fuse plug, a body, a terminal member secured in said body, saidterminal member having a hollow portion, a fuse strip having one endinserted into said hollow portion, and a spring retaining member ofelectrical conducting material inserted into said hollow portion to bearagainst the wall of the hollow portion and against the end of said stripand force said end into contact with the wall of said hollow portion.

2. In a fuse plug, a body, a terminal member secured in said body, saidterminal member having a hollow portion, a fuse strip having one endinserted into said hollow portion, and a substantially U-shapedresilient retaining member inserted into said hollow portion to have oneleg bear against the wall of the hollow portion and the other leg tobear against the end of said strip and force it into contact with thewall of said hollow portion.

3. In a fuse plug, a body, a terminal member secured in said body, saidterminal member having a hollow portion of substantially square shape incross section, a fuse strip having one end inserted into said hollowportion, and a resilient retaining member inserted into said hollowportion to bear against the end of said strip and force it into contactwith the wall of said hollow portion.

4. In a fuse plug, a body, a terminal secured in said body, saidterminal having a hollow por-- tion communicating with the interior ofsaid body, a fuse strip having one end inserted in said hollow portionand a retaining member of substantially U-shape, said retaining memberbeing inserted into said hollow portion and resiliently locking the endof said strip therein.

5. In a fuse plug, a body having a through opening, a terminal memberhaving a hollow portion fitting snugly in said through opening, a fusestrip having one end inserted in said hollow portion, a substantiallyU-shaped spring member inserted in said hollow portion to retain the endof said strip therein, the upper edge portions of said hollow portionbeing clinched to said body in opposite relation between the legs ofsaid retaining member to prevent separation of the terminal from thebody.

6. In a fuse plug, a body having a through opening of substantiallysquare cross section, a terminal member having a hollow portion fittingsnugly in said through opening, a fuse strip having one end inserted insaid hollow portion, a substantially U-shaped spring member inserted insaid hollow portion to retain the end of said strip therein, theopposite upper edges of said hollow portion between the legs of saidretaining member being outturned over the upper edges of the throughopening to prevent withdrawal of the terminal from the body.

7. In a fuse plug, a body having a through opening of substantiallycross section, a terminal member having a hollow portion fitting snuglyin said through opening, a fuse strip having one end inserted in saidhollow portion, a substantially U-shaped spring member inserted in saidhollow portion to retain the end of said strip therein, the upper edgeportions of said hollow portion being clinched to said body in oppositerelation between the legs of said retaining member.

LAMBERT SCHMIDT.

